$\dfrac{-2}{3} \div 2\dfrac{1}{4} = $
Explanation: Let's start by converting the mixed number to a fraction. $\phantom{=}\dfrac{-2}{3} \div 2\dfrac{1}{4}$ $=\dfrac{-2}{3} \div \dfrac{9}{4}$ $=\dfrac{-2}{3} \cdot \dfrac{4}{9}~~~~~~~\text{multiply by the reciprocal}$ $=\dfrac{-8}{27}$ $=-\dfrac{8}{27}$